Bertrand Traore has been very impressive for Vitesse Arnhem during the 2014/15 season(Getty)

Vitesse Arnhem coach Peter Bosz has revealed that Jose Mourinho is "crazy" about youngster Bertrand Traore after impressing during his loan spell at Eredivisie last season.

The 19-year-old was a part of the Blues' pre-season squad in 2013. The former Real Madrid manager was impressed by his skills and described him as "one of the best talents of his age". However, delay in work permit forced the Premier League champions to secure his services only in January 2014.

Traore spent the last 18 months on loan at Vitesse and he played a crucial role in helping the Dutch side qualify for the Europa League by finishing third in the league table. The Burkina Faso international scored 13 goals and managed four assists during the 2014/15 season.

"Jose Mourinho is crazy about him. If the opportunity is there, they prefer to take him back," Bosz told De Telegraaf.

Meanwhile, Traore has expressed his delight after playing a full season with Vitesse. The African midfielder has urged Mourinho to include him in the first-team, but admitted that he is still uncertain whether he will be at Stamford Bridge or sent on-loan for the next season.

"Chelsea are very happy with my development. But I will only hear what is next in the summer," Traore explained.

"I'm ready when the opportunity comes and I'm not afraid to show my ability at Chelsea. This has been the first time I have played a full season in professional football. I've taken a huge step forward physically," he concluded.

In April, the Portuguese tactician said it would be hard for him to include several young players in Chelsea's first team.

"Some of the older ones will go on loan to play every game in the Championship or the Premier League, even abroad. And we will bring some of the younger ones into the process. But to have them all at the same time in the first-team squad is hard," Mourinho explained.